Thermal transfer sheet

ABSTRACT

A thermal transfer sheet is provided that can yield thermally transferred images, which possess excellent various fastness or resistance properties even under severe service conditions, and comprises a transferable protective layer having good transferability. In a thermal transfer sheet comprising a substrate sheet and a thermally transferable protective layer on the substrate sheet, the thermally transferable protective layer comprises a scratch-resistant layer which is repeatedly provided one by one for each picture plane unit in the thermal transfer sheet. An area of the scratch-resistant layer for each picture plane unit is smaller than an area of an object in its transfer surface. By virtue of this construction, at the time of the transfer of a protective layer onto an object, layer cutting does not occur within the scratch-resistant layer but within other layer (such as peel layer or adhesive layer), and, consequently, the protective layer can be transferred with good transferability.

BACKGROUND OF THE INVENTION

[0001] 1. Technical Field

[0002] The present invention relates to a thermal transfer sheet and anintermediate transfer recording medium that can yield prints havingthermally transferred images, which possess excellent various fastnessor resistance properties even under severe service conditions, and canrealize the transfer of a transfer portion or a protective layer onto anobject with good transferability.

[0003] 2. Prior Art

[0004] Thermal transfer has become extensively used as a simple printingmethod. The thermal transfer is a method which comprises the steps of:putting a thermal transfer sheet, comprising a colorant layer providedon one side of a substrate sheet, on top of a thermal transferimage-receiving sheet optionally provided with an image-receptive layer;and image-wise heating the backside of the thermal transfer sheet byheating means such as a thermal head to selectively transfer thecolorant contained in the colorant layer to form an image on the thermaltransfer image-receiving sheet.

[0005] Thermal transfer methods are classified into thermal ink transfer(hot melt-type thermal transfer) and thermal dye sublimation transfer(sublimation-type thermal transfer). The thermal ink transfer is amethod for image formation wherein a thermal transfer sheet comprising asubstrate sheet, such as a PET film, bearing thereon a hot-melt inklayer, comprising a dispersion of a colorant, such as a pigment, in abinder, such as a hot-melt wax or resin, is provided and energyaccording to image information is applied to heating means such as athermal head to transfer the colorant together with the binder onto athermal transfer image-receiving sheet such as paper or plastic sheets.Images produced by the thermal ink transfer have high density andpossess high sharpness and are suitable for recording binary images ofcharacters or the like.

[0006] On the other hand, the thermal dye sublimation transfer is amethod for image formation which comprises the steps of: providing athermal transfer sheet comprising a substrate sheet, such as a PET film,bearing thereon a dye layer comprising a dye, which is mainly thermallytransferred by sublimation, dissolved or dispersed in a resin binder;and applying energy according to image information to heating means suchas a thermal head to transfer only the dye onto a thermal transferimage-receiving sheet comprising a substrate sheet, such as paper or aplastic, optionally provided with a dye-receptive layer. The thermal dyesublimation transfer can regulate the amount of the dye transferredaccording to the quantity of energy applied and thus can form gradationimages of which the image density has been regulated dot by dot of thethermal head. Further, since the colorant used is a dye, the formedimage is transparent, and the reproduction of intermediate colorsproduced by superimposing different color dyes on top of each other orone another is excellent. Accordingly, high-quality photograph-like fullcolor images can be formed with excellent reproduction of intermediatecolors by transferring different color dyes, such as yellow, magenta,cyan, and black, onto a thermal transfer image-receiving sheet, so as tosuperimpose the color dyes on top of each other or one another, from athermal transfer sheet of the different colors.

[0007] These thermal transfer methods can simply form various images andthus have become utilized in the formation of prints the number of whichmay be relatively small. Thermal transfer sheets used with these thermaltransfer methods have various practical applications. Representativeexamples of applications include proof sheets, and recording sheets foroutput images, output plans or designs drawn by CAD/CAM or the like, orimages output from a variety of medical analyzers or measuringinstruments such as CT scanners and endoscopic cameras. They can also beused as the alternative of instant photographs, and as paper forproducing identity certifications, ID cards, credit cards, and othercards on which facial photographs or the like are printed, or forproducing synthetic or memorial photographs which are taken at amusementfacilities such as recreation parks, game centers, museums, aquariumsand the like.

[0008] When ID cards such as identity certifications are prepared usingthe above thermal transfer sheet, the thermal ink transfer method caneasily form binary images of characters, numerals and the like. Thethermal ink transfer method, however, is unsuitable for the formation ofimages required to have high quality, such as a photograph of a face.Further, the formed images are disadvantageously poor in fastness orresistance properties, particularly abrasion resistance. On the otherhand, the thermal dye sublimation transfer is suitable for the formationof gradation images such as a photograph of a face. Unlike images formedusing printing ink, the images formed by thermal dye sublimationtransfer, however, do not contain any vehicle and thus aredisadvantageously poor in fastness and resistance properties such aslightfastness and weathering resistance.

[0009] In order to overcome the above drawbacks, a method has beenadopted wherein a transparent film is laminated onto the surface of theformed image. This method, however, involves a complicate operation. Inaddition, in this method, since lamination is carried out on the wholeobject, curling occurs in the object. Further, a very thin film cannotbe used for reasons of laminating operation. This inevitably increasesthe thickness of the whole print.

[0010] In order to solve these drawbacks, a method has been proposedwherein a protective layer transfer sheet comprising a substrate filmand a transferable resin layer (a protective layer) provided on thesubstrate film is provided and the transferable resin layer istransferred to provide a protective layer on at least a part of theimage. According to this method, fastness or resistance properties suchas chemical resistance and lightfastness can be improved to some extent.The fastness and resistance properties of the thermally transferredimage, however, are not yet satisfactory under severe practical serviceconditions. The protective layer transfer sheet is advantageous in thatthe size of the protective layer (resin layer) transferred can beproperly varied, but on the other hand, a tendency toward an increase inprotective layer transfer processing speed has made it difficult totransfer the protective layer with good transferability. The protectivelayer transfer sheet has many additional disadvantages including that,when the fastness or resistance properties of the protective layer, suchas heat resistance is improved, heat applied at the time of the transferof the protective layer is likely to deteriorate the transferability.

[0011] The diversification of the applications has led to a demand forthe formation of a thermally transferred image on a desired object. Amethod has been proposed, as one method for meeting this demand, whereina colorant such as a dye or a pigment is transferred, from a thermaltransfer sheet comprising a dye layer or a hot-melt ink layer, onto areceptive layer in an intermediate transfer recording medium comprisingthe receptive layer separably provided on a substrate to form an imageon the receptive layer and, thereafter, the intermediate transferrecording medium is heated to transfer the receptive layer, with theimage formed thereon, onto an object (Japanese Patent Laid-Open No.238791/1987 or the like).

[0012] Since the use of the intermediate transfer recording mediumpermits the receptive layer to be transferred onto an object, thismethod is preferably used, for example, for objects, onto which acolorant is less likely to be transferred making it impossible to formhigh-quality images directly on them, and objects which are likely to befused to the colorant layer at the time of thermal transfer. Further, amethod may be adopted wherein necessary matter such as a signature ispreviously written or printed on an object and, thereafter, a transferportion, with an image of characters, photographs or the like beingformed thereon, is transferred from an intermediate transfer recordingmedium. Therefore, the intermediate transfer recording medium ispreferably used in the preparation of passports or other identitycertifications, credit cards/ID cards, or other prints.

[0013] The present applicant has proposed in Japanese Patent Laid-OpenNo. 315639/1998 a receptive layer transfer sheet (an intermediatetransfer medium film) wherein, in order to impart fastness andresistance properties, such as lightfastness, weathering resistance, andabrasion resistance, to thermally transferred images on objects such asID cards, an ionizing radiation-cured resin layer and a receptive layerare separably provided on a substrate.

[0014] When the above intermediate transfer recording medium is used,the fastness and resistance properties of the thermally transferredimage can be improved. However, the hardness of the ionizingradiation-cured resin layer is so hard that the ionizing radiation-curedresin layer cannot conform to the flexibility of the object, leading tothe deformation of the object between the transfer portion and thenon-transfer portion of the intermediate transfer recording medium.Further, in transferring the intermediate transfer recording medium ontoan object, due to a tendency toward an increase in transfer processingspeed, the transferability of the intermediate transfer recording mediumis unsatisfactory, and, in this case, for example, uneven edge of thetransferred portion or uneven transferred portion, which isdisadvantageous from the practical point of view, occurs.

SUMMARY OF THE INVENTION

[0015] Accordingly, it is an object of the present invention to solvethe above problems of the prior art and to provide a thermal transfersheet that can yield thermally transferred images, which possessexcellent various fastness or resistance properties even under severeservice conditions, and comprises a transferable protective layer havinggood transferability.

[0016] It is another object of the present invention to provide anintermediate transfer recording medium, comprising at least a peellayer, a cured product of an ionizing radiation-curable resin layer, anda receptive layer provided in that order on a substrate film, that canyield prints having a thermally transferred image possessing excellentvarious fastness and resistance properties even under severe serviceconditions, has good transferability, and can prevent the deformation ofan object between the transfer portion and the non-transfer portion ofthe intermediate transfer recording medium, and to provide a print.

[0017] The above object can be attained by a first thermal transfersheet according to the present invention, comprising a substrate sheetand a thermally transferable protective layer provided on the substratesheet, wherein the thermally transferable protective layer comprises ascratch-resistant layer; the scratch-resistant layer is repeatedlyprovided one by one for each picture plane unit in the thermal transfersheet; and an area of the scratch-resistant layer for each picture planeunit is smaller than an area of an object in its transfer surface. Inother words, the area of the object in its transfer surface can also besaid to be the size of the outward form of the protective layer formedby the transfer of the thermally transferable protective layer onto theobject. The thermally transferable protective layer preferably comprisesa peel layer, the scratch-resistant layer, and an adhesive layerprovided in that order as viewed from the substrate sheet side.According to this construction, at the time of the transfer of aprotective layer onto an object, layer cutting does not occur within thescratch-resistant layer but within other layer (such as peel layer oradhesive layer), and, consequently, the protective layer can betransferred with good transferability.

[0018] The scratch-resistant layer is preferably formed from an ionizingradiation-curable resin. Upon exposure to an ultraviolet light or anelectron beam, an ionizing radiation-curable resin layer causescrosslinking to form a scratch-resistant layer having athree-dimensional network structure which is strong and possessesexcellent various fastness and resistance properties. Further, theprotective layer is not cut within the scratch-resistant layer butwithin the peel layer or adhesive layer having good transferability andis transferred onto an object. The use of the thermal transfer sheetaccording to the present invention can realize excellent variousfastness and resistance properties of thermally transferred images andgood transferability in the transfer of a protective layer onto anobject even under severe service conditions.

[0019] The second thermal transfer sheet according to the presentinvention comprises a substrate sheet and a thermally transferableprotective layer provided on the substrate sheet, wherein the thermallytransferable protective layer comprises at least a peel layer, a thermaltransfer resin layer, and an adhesive layer provided in that order asviewed from the substrate sheet side, and the thermal transfer resinlayer comprises a cured product of an ionizing radiation-curable resin.According to this construction, in the formation of the thermal transferresin layer, upon exposure to ultraviolet light or electron beam, theionizing radiation-curable resin layer causes crosslinking and forms athree-dimensional network structure which is strong and possessesexcellent various fastness and resistance properties. In the thermaltransfer sheet according to the present invention, in order to ensurethe fixation of the protective layer onto the object, an adhesive layeris provided on the thermal transfer resin layer, and, in addition, apeel layer is provided between the substrate sheet and the thermaltransfer resin layer so that, in the transfer of the protective layeronto the object, the protective layer is faithfully separated from thesubstrate sheet (that is, so that uneven transfer of the protectivelayer can be avoided). The use of this thermal transfer sheet canrealize excellent various fastness and resistance properties ofthermally transferred images and good transferability of the protectivelayer onto the object even under severe service conditions.

[0020] In the thermal transfer sheet according to the present invention,preferably, a thermally transferable colorant layer(s) for at least onecolor is provided on the substrate sheet, the thermally transferableprotective layer is then provided on the substrate sheet so that thethermally transferable colorant layer and the thermally transferableprotective layer constitute one picture plane unit, and a combination ofthe thermally transferable colorant layer with the thermallytransferable protective layer is repeatedly provided in a face serialmanner for constituting each picture plane unit. In this case, there isno need to provide two thermal transfer sheets, i.e., a thermal transfersheet for transferring a protective layer and a thermal transfer sheetfor forming a thermally transferred image, and the provision of only onethermal transfer sheet suffices for the formation of a thermallytransferred image and the transfer of a protective layer. Thus, theefficiency is very high, and, in addition, the production cost of athermal transfer sheet can be reduced.

[0021] The ionizing radiation-curable resin is preferably aurethane-modified acrylic base resin, and, particularly preferably, 5 to40 parts by weight, based on 100 parts by weight of theurethane-modified acrylic base resin, of an oligomer is contained. Inthis case, the protective layer is flexible, and, in addition, printshaving a thermally transferred image can be obtained which possessexcellent fastness and resistance properties such as excellent chemicalresistance, lightfastness, and weathering resistance.

[0022] According to the present invention, there is provided anintermediate transfer recording medium comprising a substrate film and atransfer portion provided on the substrate film, wherein said transferportion comprises at least a peel layer, a cured product of an ionizingradiation-curable resin layer, and a receptive layer provided in thatorder as viewed from the substrate film side, and the ionizingradiation-curable resin layer comprises an urethane-modified acrylicbase resin. Upon exposure to ultraviolet light or electron beam, theionizing radiation-curable resin layer causes crosslinking to form anionizing radiation-cured resin layer having a three-dimensional networkstructure which is strong and possesses excellent various fastness andresistance properties. In the ionizing radiation-curable resin layer,particularly preferably, 5 to 40 parts by weight, based on 100 parts byweight, of the urethane-modified acrylic base resin, of an oligomer iscontained. In this case, the protective layer transferred onto theobject is highly flexible, and the deformation of an object between thetransfer portion and the non-transfer portion of the intermediatetransfer recording medium can be prevented. This is consideredattributable to a difference in shrinkage between the transfer portionand the non-transfer portion.

[0023] In the intermediate transfer recording medium according to thepresent invention, at least a peel layer, a cured product of an ionizingradiation-curable resin layer, and a receptive layer are provided inthat order on a substrate film to constitute a transfer portion. Thetransfer portion can be transferred onto an object without any uneventransfer and with even edge of the transferred portion, that is, withgood transferability.

[0024] Further, according to the present invention, there is provided aprint produced by providing the above intermediate transfer recordingmedium, wherein the print is obtained by the steps of forming a thermaltransfer image on the intermediate transfer recording medium in itstransfer portion, and transferring the transfer portion with the imageformed thereon onto an object.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025]FIG. 1A is a schematic cross-sectional view showing an embodimentof the first thermal transfer sheet according to the present invention;

[0026]FIG. 1B is a schematic plan view showing another embodiment of thefirst thermal transfer sheet according to the present invention;

[0027]FIG. 1C is a schematic explanatory view showing an embodimentwherein a protective layer is thermally transferred onto an object usingthe first thermal transfer sheet according to the present invention;

[0028]FIG. 1D is a schematic cross-sectional view showing an assemblyafter the transfer of a thermally transferable protective layer, usingthe first thermal transfer sheet according to the present invention,onto an object with a thermally transferred image formed thereon;

[0029]FIG. 2A is a schematic cross-sectional view showing an embodimentof the second thermal transfer sheet according to the present invention;

[0030]FIG. 2B is a schematic plan view showing another embodiment of thesecond thermal transfer sheet according to the present invention;

[0031]FIG. 2C is a schematic explanatory view showing an embodimentwherein a protective layer is thermally transferred onto an object usingthe second thermal transfer sheet according to the present invention;

[0032]FIG. 2D is a schematic cross-sectional view showing an assemblyafter the transfer of a thermally transferable protective layer, usingthe second thermal transfer sheet according to the present invention,onto an object with a thermally transferred image formed thereon;

[0033]FIG. 3A is a cross-sectional view showing one embodiment of theintermediate transfer recording medium according to the presentinvention; and

[0034]FIG. 3B is a cross-sectional view showing one embodiment of theprint according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0035] The first thermal transfer sheet according to the presentinvention will be explained with reference to the accompanying drawings.

[0036]FIG. 1A is a schematic cross-sectional view showing one embodimentof the first thermal transfer sheet 101 according to the presentinvention. In the first thermal transfer sheet 101, a peel layer 103, ascratch-resistant layer 104, and an adhesive layer 105 are provided inthat order on a substrate sheet 102. In this case, three layers of thepeel layer 103, the scratch-resistant layer 104, and the adhesive layer105 provided on the substrate sheet 102 constitute a thermallytransferable protective layer 106. That is, the thermally transferableprotective layer 106 is constituted by the scratch-resistant layer 104and other layers, i.e., the peel layer 103 and the adhesive layer 105.At the same time, in the thermal transfer sheet 101, thescratch-resistant layer 104 is repeatedly provided one by one on thesubstrate sheet 102 for each picture plane unit. In this case, the sizeof the scratch-resistant layer 104 is smaller than the size A of anobject in its transfer surface. By virtue of this construction, at thetime of the transfer of the protective layer 106 onto an object, layercutting does not occur in the scratch-resistant layer 104 but within theadhesive layer 105 (and the peel layer 103), and, consequently, theprotective layer can be transferred with good transferability. Aheat-resistant slip layer (not shown) can be provided on the substratesheet 102 in its surface remote from the thermally transferableprotective layer 106 from the viewpoint of preventing sticking, cocklingand other unfavorable phenomena caused by heat of a thermal head, a heatroll or the like.

[0037]FIG. 1B is a schematic plan view showing another embodiment of thefirst thermal transfer sheet 101 according to the present invention. Inthis embodiment, thermally transferable colorant layers 107 of yellow(Y), magenta (M), and cyan (C) are provided on a substrate sheet 102 anda thermally transferable protective layer 106 is then provided on thesubstrate sheet 102. One unit (U) of a combination of the thermallytransferable colorant layers 107 with the thermally transferableprotective layer 106 is then repeatedly provided in a face serialmanner. The thermally transferable protective layer comprises at least ascratch-resistant layer and other layers, although these layers are notshown because the drawing is not a cross-sectional view but a plan view.

[0038]FIG. 1C is a schematic explanatory view showing an embodimentwherein a protective layer 106 is thermally transferred onto an object108 using the first thermal transfer sheet 101 according to the presentinvention. In this embodiment, thermally transferable colorant layers107 of at least three colors of yellow, magenta, and cyan are providedon a substrate sheet 102, and a thermally transferable protective layer106 is then provided on the substrate sheet 102. One unit of acombination of the thermally transferable colorant layers 107 with thethermally transferable protective layer 106 is repeatedly formed in aface serial manner to form the thermal transfer sheet 101. The thermaltransfer sheet 101 is used to thermally transfer the colorant layer 107in the thermal transfer sheet 101 onto the object 108 by means of athermal head 110 to form an image 109. The protective layer 106 isthermally transferred by the thermal head 110 from the thermal transfersheet 101 onto the image 109 so as to cover at least the printedportion, and the substrate sheet 102 is then separated from the object108. Although the layer construction of the thermally transferableprotective layer is not shown, the scratch-resistant layer has a sizesmaller than the size of the protective layer 106 thermally transferredonto the object 108 and covers the printed image.

[0039]FIG. 1D is a schematic cross-sectional view showing an assemblyafter the transfer of a thermally transferable protective layer, usingthe first thermal transfer sheet according to the present invention,onto an object with a thermally transferred image formed thereon.

[0040] A receptive layer 112 is previously formed on an object 108, anda thermally transferred image 109 is then formed on the receptive layerusing a thermal transfer sheet comprising thermally transferablecolorant layers provided on a substrate. Thereafter, a protective layer106 is transferred using the thermal transfer sheet according to thepresent invention provided with the thermally transferable protectivelayer 106 so as to cover the thermally transferred image 109. Theadhesive layer 105 is transferred onto a portion which comes intocontact with the thermally transferred image 109, and thescratch-resistant layer 104 is stacked onto the adhesive layer 105 sothat the size of the scratch-resistant layer 104 is smaller than thesize of the transferred adhesive layer 105.

[0041] Thermal Transfer Sheet

[0042] Substrate Sheet:

[0043] In the thermal transfer sheet according to the present invention,any substrate sheet used in conventional thermal transfer sheets may beused so far as the substrate sheet has some level of heat resistance andstrength, and examples thereof include tissue papers, such as glassinepaper, capacitor paper, and paraffin paper; and films of plastics, forexample, polyesters, such as polyethylene terephthalate and polyethylenenaphthalate, polypropylene, cellophane, polycarbonate, celluloseacetate, polyethylene, polyvinyl chloride, polystyrene, nylon,polyimide, polyvinylidene chloride, and ionomers. The thickness of thesubstrate sheet may be properly varied depending upon materials for thesubstrate sheet so that the substrate sheet has proper strength, heatresistance and other properties. However, the thickness is 2 to 100 μm,preferably about 10 to 80 μm.

[0044] In order to regulate the surface gloss of the print after thetransfer of the protective layer, a matte polyethylene terephthalatefilm may be used as the substrate sheet. Sandblasting, incorporation,internal foaming and the like may be mentioned as means for matting.

[0045] Peel Layer:

[0046] In the thermal transfer sheet according to the present invention,the scratch-resistant layer is preferably provided on the substratesheet through a peel layer 103. The provision of the peel layer permitsthe scratch-resistant layer to be surely and easily transferred from thethermal transfer sheet onto an object.

[0047] The peel layer may comprise, for example, waxes, such asmicrocrystalline wax, carnauba wax, paraffin wax, Fischer-Tropsh wax,various types of low-molecular weight polyethylene, Japan wax, beeswax,spermaceti, insect wax, wool wax, shellac wax, candelilla wax,petrolactum, partially modified wax, fatty esters, and fatty amides, andthermoplastic resins, such as silicone wax, silicone resin, fluororesin,acrylic resin, polyester resin, polyurethane resin, cellulose resin,vinyl chloride-vinyl acetate copolymer, and nitrocellulose.

[0048] Further, the peel layer may comprise a binder resin and areleasable material. Binder resins usable herein include thermoplasticresins, for example, acrylic resins, such as polymethyl methacrylate,polyethyl methacrylate, polybutyl acrylate, vinyl resins, such aspolyvinyl acetate, vinyl chloride-vinyl acetate copolymer, polyvinylalcohol, and polyvinylbutyral, and cellulose derivatives, such asethylcellulose, nitrocellulose, and cellulose acetate, and thermosettingresins, for example, unsaturated polyester resins, polyester resins,polyurethane resins, and aminoalkyd resins. Releasable materials includewaxes, silicone wax, silicone resins, melamine resins, fluororesins,fine powders of talc or silica, and lubricants such as surfactants ormetal soaps.

[0049] The peel layer may be formed by dissolving or dispersing theabove-described necessary materials in a suitable solvent to prepare acoating liquid for a peel layer, coating the coating liquid onto asubstrate sheet by gravure printing, screen printing, reverse coatingusing a gravure plate or other means, and drying the coating. Thecoverage is generally 0.1 to 10 g/m² on a dry basis.

[0050] Scratch-Resistant Layer:

[0051] The first thermal transfer sheet according to the presentinvention comprises a substrate sheet and, provided on the substratesheet, at least a scratch-resistant layer and other layers whichconstitute a thermally transferable protective layer.

[0052] In the thermally transferable protective layer, thescratch-resistant layer 104 mainly functions to impart various fastnessand resistance properties to thermally transferred images. Thisscratch-resistant layer preferably comprises a cured product of anionizing radiation-curable resin and will be specifically describedbelow.

[0053] A composition prepared by properly mixing prepolymers, oligomersand/or monomers containing, in the molecule thereof, polymerizalbeunsaturated bonds, such as (meth)acryloyl and (meth)acryloyloxy groups((meth)acryloyl referring to acryloyl or methacryloyl; for (meth), thesame shall apply hereinafter) or epoxy group together may be mentionedas the ionizing radiation-curable resin. Prepolymers and oligomersinclude acrylates, such as urethane(meth)acrylate,polyester(meth)acrylate, and epoxy(meth)acrylate, silicone resins suchas siloxane, and unsaturated polyesters, and epoxy.

[0054] Examples of monomers include styrene monomers such as styrene andα-methylstyrene, methyl(meth)acrylate, (meth)acrylic acid-2-ethylhexyl,dipentaerythritol hexa(meth)acrylate, dipentaerythritolpenta(meth)-acrylate, trimethylolpropane tri(meth)acrylate, and/orpolyol compounds containing, in the molecule thereof, two or more thiolgroups, for example, trimethyolpropane trithioglycolate,trimethyolpropane trithiopropylate, and pentaerythritol tetrathioglycol.One of or a mixture of two or more of the above compounds is usedaccording to need. In order to impart ordinary coatability to the resincomposition, the resin composition preferably comprises not less than 5%by weight of the prepolymer or the oligomer and not more than 95% byweight of the monomer and/or polythiol.

[0055] In the selection of the monomer, when the cured product isrequired to be flexible, a structure having a relatively low degree ofcrosslinking is adopted by bringing the amount of the monomer to arelatively small one or using a monofunctional or bifuctional acrylatemonomer with caution so as not to sacrifice various fastness andresistance properties of the scratch-resistant layer and thecoatability.

[0056] For example, when the cured product is required to be heatresistant, hard, or resistant to solvents, a structure having a highdegree of crosslinking is preferably adopted by bringing the amount ofthe monomer to a relatively large one with caution so as not tosacrifice the coatability or using a tri- or higher functional acrylatemonomer. A method may also be used wherein a monofunctional orbifunctional monomer is mixed with a tri- or higher functional monomerto regulate coatability and properties of the cured product.

[0057] Monofunctional acrylate monomers include 2-hydroxy acrylate,2-hexyl acrylate, and phenoxyethyl acrylate. Bifunctional acrylatemonomers include ethylene glycol diacrylate and 1,6-hexanedioldiacrylate, and tri- or higher functional acrylate monomers includetrimethylol propane triacrylate, pentaerythritol hexaacrylate, anddipentaerythritol hexaacrylate.

[0058] A mixture of at least one of the above prepolymers, oligomers,and monomers with about 1 to 50% by weight of the following ionizingradiation-non-curable resin may be used from the viewpoint of regulatingproperties of the cured product such as flexibility and surfacehardness. Ionizing radiation-non-curable resins include urethane,cellulosic, polyester, acrylic, butyral, polyvinyl chloride, polyvinylacetate and other thermoplastic resins.

[0059] The scratch-resistant layer of the thermal transfer sheetaccording to the present invention has excellent various fastness andresistance properties and a suitable level of flexibility, which affectshandleability, appearance, etc. of prints after transfer, and thus ispreferably formed from a urethane-modified acrylic base resin as anionizing radiation-curable resin. Further, the use of an ionizingradiation-curable resin comprising the urethane-modified acrylic baseresin and 5 to 40 parts by weight, based on 100 parts by weight of theurethane-modified acrylic base resin, of an oligomer is suitable.

[0060] The urethane-modified acrylic base resin contains a urethane bondtherein produced as a result of a reaction of a hydroxyl group (—OH)present in the acrylic resin with an isocyanate (—NCO), and, preferably,5 to 40 parts by weight of an oligomer is contained based on 100 partsby weight of the urethane-modified acrylic base resin. This can impartan excellent function, i.e., a combination of flexibility with fastnessand resistance properties, to the protective layer. Regarding theadditive to the urethane-modified acrylic base resin, in addition to theoligomer, monomers may also be of course added. When the amount of theoligomer used is small, the strength, fastness and resistance propertiesand other properties of the resin layer are unsatisfactory. On the otherhand, when the amount of the oligomer used is excessively large, thetackiness of the surface of the resin layer is so high that, forexample, blocking is disadvantageously likely to occur.

[0061] When the ionizing radiation-curable resin is cured by ionizingradiation irradiation, a transparent resin should be used.Photopolymerization initiators, such as acetophenones, benzophenones,Michler's benzoyl benzoate, a-amyloxime ester, tetramethylthiurammonosulfide, and thioxanthones, and/or photosensitizers, such asn-butylamine, triethylamine, and tri-n-butylphosphine, may beincorporated into the ionizing radiation-curable resin composition.Further, preferably, silicone resins, waxes, fluororesins, melanineresins, surfactants or the like is incorporated from the viewpoint ofreleasability.

[0062] In the present invention, ultraviolet light is mainly used forfully curing the thermal transfer resin layer comprising the ionizingradiation-curable resin-containing resin composition on the substratesheet. However, among electromagnetic radiations or charged particlebeams, visible light, γ radiation, and X radiation, which are ionizingradiations having energy quantum capable of polymerizing or crosslinkingmolecules, are also usable.

[0063] An ultraviolet irradiation device is generally used as anionizing radiation irradiation device. Ultrahigh-pressure mercury lamp,high-pressure mercury lamp, low-pressure mercury lamp, carbon arc,blacklight, a metal halide lamp and other light sources are usable asthe ultraviolet irradiation device. Electrons having an energy of 100 to1000 KeV, preferably 100 to 300 KeV, are applied from the device. Theexposure is generally about 5 to 300 KGy (kilogray).

[0064] The scratch-resistant layer may be formed by dissolving ordispersing a composition containing an ionizing radiation-curable resinfor the scratch-resistant layer in a suitable solvent to prepare an inkfor a thermal transfer resin layer, coating the ink onto the substratesheet by coating means, such as gravure printing, screen printing, orreverse coating using a gravure plate, and drying the coating.

[0065] The scratch-resistant layer may be formed in any desiredthickness on the substrate sheet. The thickness, however, is 0.1 to 50g/m², preferably about 1 to 20 g/m², on a dry basis.

[0066] Adhesive Layer:

[0067] An adhesive layer 105 may be provided on the surface of thethermally transferable protective layer in the thermal transfer sheetaccording to the present invention from the viewpoint of improving thetransferability and adhesion to prints as the object. The adhesive layermay comprise any of conventional pressure-sensitive adhesives orheat-sensitive adhesives, preferably comprise a thermoplastic resinhaving a glass transition temperature (Tg) of 50° C. to 80° C.Preferably, for example, a resin having a suitable glass transitiontemperature is selected from resins having good thermal adhesion, suchas polyester resins, vinyl chloride-vinyl acetate copolymer resins,acrylic resins, butyral resins, epoxy resins, polyamide resins, andvinyl chloride resins. The above resin preferably has low molecularweight from the viewpoint of adhesion or when the adhesive layer isformed as a pattern on a part of the thermally transferable protectivelayer, rather than the whole area of the thermally transferableprotective layer, by heating means such as a thermal head.

[0068] A coating liquid prepared by optionally adding additives such asinorganic or organic fillers to the above resin for the adhesive layeris coated by the same coating means as used in the formation of thethermal transfer resin layer, and the coating is then dried to form anadhesive layer preferably at a coverage of about 0.5 to 10 g/m² on a drybasis.

[0069] In the first thermal transfer sheet according to the presentinvention, an antistatic layer may be provided on the outermost surfaceof the thermal transfer sheet on its side where the thermallytransferable protective layer is provided, or on the outermost surfaceof the thermal transfer sheet in its side remote from the thermallytransferable protective layer, or on the outermost surface of thethermal transfer sheet on its both sides. The antistatic layer may beformed by dissolving or dispersing an antistatic agent, such as a fattyester, a sulfuric ester, a phosphoric ester, an amide, a quaternaryammonium salt, a betaine, an amino acid, an acrylic resin, or anethylene oxide adduct, in a solvent to prepare a solution or adispersion and coating the solution or the dispersion. Means for theformation of the antistatic layer may be the same as described above inconnection with the formation of the scratch-resistant layer. Thecoverage of the antistatic layer is preferably 0.001 to 0.1 g/m² on adry basis.

[0070] An intermediate layer comprising various resins may be providedbetween the peel layer and the scratch-resistant layer or between thescratch-resistant layer and the adhesive layer. The intermediate layeris preferably transparent so that the thermally transferred image can beseen through the intermediate layer. Excellent function can be added tothe thermal transfer sheet by imparting various functions to theintermediate layer. For example, resins having high level of elasticdeformation or plastic deformation, for example, polyolefin resin, vinylcopolymer resin, polyurethane resin, and polyamide resin, may be used asresins for imparting cushioning properties. Further, in order to impartantistatic capability to the intermediate layer, the intermediate layermay be formed by adding the above antistatic agent to the resin forimparting cushioning properties, dissolving or dispersing the mixture ina solvent to prepare a solution or a dispersion, and coating thesolution or the dispersion.

[0071] Next, the second thermal transfer sheet according to the presentinvention will be explained.

[0072]FIG. 2A is a schematic cross-sectional view showing one embodimentof the second thermal transfer sheet 101 according to the presentinvention. In this embodiment, a peel layer 103, a thermal transferresin layer 204, and an adhesive layer 105 are provided in that order ona substrate sheet 102. In this case, three layers of the peel layer 103,the thermal transfer resin layer 204, and the adhesive layer 105provided on the substrate sheet 102 constitute a thermally transferableprotective layer 106. The thermal transfer resin layer 104 comprises acured product of an ionizing radiation-curable resin. A heat-resistantslip layer (not shown) can be provided on the substrate sheet 102 in itssurface remote from the thermally transferable protective layer 106 fromthe viewpoint of preventing sticking, cockling and other unfavorablephenomena caused by heat of a thermal head, a heat roll or the like.

[0073]FIG. 2B is a schematic plan view showing an embodiment of thesecond thermal transfer sheet 101 according to the present invention. Inthis embodiment, thermally transferable colorant layers 107 of yellow(Y) magenta (M), and cyan (C) are provided on a substrate sheet and athermally transferable protective layer 106 is then provided on thesubstrate sheet. One unit (U) of a combination of the thermallytransferable colorant layers 107 with the thermally transferableprotective layer 106 is then repeatedly provided in a face serialmanner. The thermally transferable protective layer comprises at least apeel layer, a thermal transfer resin layer, and an adhesive layer,although these layers are not shown because the drawing is not across-sectional view but a plan view.

[0074]FIG. 2C is a schematic explanatory view showing an embodimentwherein a protective layer 106 is thermally transferred onto an object108 using the second thermal transfer sheet 101 according to oneembodiment of the present invention. In this case, thermallytransferable colorant layers 107 of at least three colors of yellow,magenta, and cyan are provided on a substrate sheet 102, and a thermallytransferable protective layer 106 is then provided on the substratesheet 102. One unit of a combination of the thermally transferablecolorant layers 107 with the thermally transferable protective layer 106is repeatedly formed in a face serial manner to form the thermaltransfer sheet 101. The thermal transfer sheet 101 is used to thermallytransfer the colorant layer 107 in the thermal transfer sheet 101 ontothe object 108 by means of a thermal head 110 to form an image 109. Theprotective layer 106 is thermally transferred by the thermal head 110from the thermal transfer sheet 101 onto the image 109 so as to cover atleast the printed portion, and the substrate sheet 102 is then separatedfrom the object 108.

[0075]FIG. 2D is a schematic cross-sectional view showing an assemblyafter the transfer of a thermally transferable protective layer, usingthe second thermal transfer sheet according to the present invention,onto an object with a thermally transferred image formed thereon.

[0076] A receptive layer 112 is previously formed on an object 108, anda thermally transferred image 109 is then formed on the receptive layerusing a thermal transfer sheet comprising thermally transferablecolorant layers provided on a substrate. Thereafter, a protective layer106 is transferred using the thermal transfer sheet according to thepresent invention provided with the thermally transferable protectivelayer 106 so as to cover the thermally transferred image 109. Theadhesive layer 105 is transferred onto a portion which comes intocontact with the thermally transferred image 109, and thescratch-resistant layer 104 is stacked onto the adhesive layer 105 sothat the size of the scratch-resistant layer 104 is smaller than thesize of the transferred adhesive layer 105.

[0077] The substrate sheet constituting the second thermal transfersheet according to the present invention may be the same as that used inthe first thermal transfer sheet.

[0078] In the second thermal transfer sheet according to the presentinvention, a thermal transfer resin layer is provided on the substratesheet through the peel layer 103. The provision of the peel layerpermits the thermal transfer resin layer and the adhesive layer providedon the resin layer to be surely and easily transferred from the thermaltransfer sheet onto an object. The peel layer may be the same as thatused in the first thermal transfer sheet.

[0079] The second thermal transfer sheet according to the presentinvention comprises a substrate sheet and, provided on the substratesheet, at least a peel layer, a thermal transfer resin layer, and anadhesive layer in that order. At least three layers of the peel layer,the thermal transfer resin layer, and the adhesive layer constitute thethermally transferable protective layer.

[0080] In the thermally transferable protective layer, the thermaltransfer resin layer 204 mainly functions to impart various fastness andresistance properties to thermally transferred images. This thermaltransfer resin layer may comprise a cured product of an ionizingradiation-curable resin which may be the same as that used in the firstthermal transfer sheet. The ionizing radiation-curable resin may becured in the same manner as described above.

[0081] The thermal transfer resin layer may be formed by dissolving ordispersing a composition containing the ionizing radiation-curable resinfor the thermal transfer resin layer in a suitable solvent to prepare anink for the formation of a thermal transfer resin layer, coating the inkonto the substrate sheet by coating means, such as gravure printing,screen printing, or reverse coating using a gravure plate, and dryingthe coating.

[0082] The thermal transfer resin layer may be formed in any desiredthickness on the substrate sheet. The thickness, however, is 0.1 to 50g/m², preferably about 1 to 20 g/m², on a dry basis.

[0083] The adhesive layer 5 constituting the thermally transferableprotective layer in the thermal transfer sheet according to the presentinvention functions to impart good transferability and adhesion ontoprints as objects to the surface of the thermally transferableprotective layer. This adhesive layer may be the same as that used inthe first thermal transfer sheet.

[0084] The second thermal transfer sheet according to the presentinvention comprises at least a substrate sheet, a peel layer, a thermaltransfer resin layer, and an adhesive layer. An antistatic layer may beprovided on the surface of the adhesive layer, on the backside of thesubstrate sheet, or on the outermost surface of the thermal transfersheet in its both sides. The antistatic layer may be the same as thatused in the first thermal transfer sheet.

[0085] Further, an intermediate layer comprising various resins may beprovided between the peel layer and the thermal transfer resin layer orbetween the thermal transfer resin layer and the adhesive layer. Theintermediate layer is preferably transparent so that the thermallytransferred image can be seen through the intermediate layer. Excellentfunction can be added to the thermal transfer sheet by imparting variousfunctions to the intermediate layer. The intermediate layer may be thesame as that used in the first thermal transfer sheet.

[0086] In the first and second thermal transfer sheets according to thepresent invention, if necessary, a heat-resistant slip layer may beprovided on the backside of the substrate sheet, that is, on the surfaceof the substrate sheet remote from the thermally transferable protectivelayer, from the viewpoint of preventing sticking, cockling and otherunfavorable phenomena caused by heat of thermal transfer means such as athermal head or a heat roll.

[0087] Any conventional resin may be used as the resin for constitutingthe heat-resistant slip layer, and examples thereof include polyvinylbutyral resins, polyvinyl acetoacetal resins, polyester resins, vinylchloride-vinyl acetate copolymers, polyether resins, polybutadieneresins, styrene-butadiene copolymers, acrylic polyols, polyurethaneacrylates, polyester acrylates, polyether acrylates, epoxy acrylates,prepolymers of urethane or epoxy, nitrocellulose resins, cellulosenitrate resins, cellulose acetopropionate resins, cellulose acetatebutyrate resins, cellulose acetate hydrodiene phthalate resins,cellulose acetate resins, aromatic polyamide resins, polyimide resins,polycarbonate resins, chlorinated polyolefin resins, and chlorinatedpolyolefin resins.

[0088] Slipperiness-imparting agents added to or topcoated on theheat-resistant slip layer comprising the above resin include phosphoricesters, silicone oils, graphite powder, silicone graft polymers, fluorograft polymers, acrylsilicone graft polymers, acrylsiloxanes,arylsiloxanes, and other silicone polymers. Preferred a layer comprisesa polyol, for example, a high-molecular polyalochol compound, apolyisocyanate compound and a phosphoric ester compound. Further, theaddition of a filler is more preferred.

[0089] The heat-resistant slip layer may be formed by dissolving ordispersing the resin, the slipperiness-imparting agent, and a filler ina suitable solvent to prepare an ink for the formation of aheat-resistant slip layer, coating the ink onto the backside of thesubstrate sheet by coating means, such as gravure printing, screenprinting, or reverse coating using a gravure plate, and drying thecoating.

[0090] Thermally Transferable Colorant Layer:

[0091] The thermally transferable colorant layer 7 provided on thesubstrate sheet in the thermal transfer sheet according to the presentinvention may be either a dye layer comprising a solution or dispersionof a dye, which is mainly thermally transferred by sublimation, in aresin binder, or a heat-fusion ink layer comprising a dispersion of acolorant such as a pigment or a dye in a binder such as heat-fusion waxor resin. Further, a method may also be used wherein, for example,colorant layers of yellow, magenta, and cyan as sublimable dye layersand a heat-fusion ink layer as a black color layer are provided incombination in a face serial manner.

[0092] The dye layer as the thermally transferable colorant layer is alayer comprising a dye supported by a proper binder resin. Dyes commonlyused in conventional thermal transfer sheets may be effectively usedwithout particular limitation. For example, MS Red G, Macrolex RedViolet R, Ceres Red 7B, Samaron Red HBSL, and Resolin Red F 3BS may bementioned as several examples of magenta dyes. Phorone Brilliant Yellow6 GL, PTY-52, Macrolex Yellow 6G and the like may be mentioned as yellowdyes. Kayaset Blue 714, Waxoline Blue AP-FW, Phorone Brilliant Blue S-R,and MS Blue 100 may be mentioned as cyan dyes.

[0093] Any conventional binder resin may be used for carrying the abovedyes, and examples of preferred binder resins include: cellulosic resinssuch as ethylcellulose, hydroxyethylcellulose, ethylhydroxy-cellulose,hydroxypropylcellulose, methylcellulose, cellulose acetate, andcellulose acetate butyrate; vinyl resins such as polyvinyl alcohol,polyvinyl acetate, polyvinyl butyral, polyvinyl acetal, polyvinylpyrrolidone, and polyacrylamide; and polyesters. Among them, forexample, cellulosic, acetal, butyral, and polyester resins are preferredfrom the viewpoints of heat resistance, transferability of dyes and thelike. Further, if necessary, various conventional other additives may beincorporated into the dye layer.

[0094] Dye layers are preferably formed by adding the sublimable dye,the binder resin and other optional ingredients to a suitable solvent todissolve or disperse the ingredients in the solvent to prepare coatingmaterials or inks for the formation of dye layers, coating the coatingmaterials or the inks in a face serial manner on the substrate film, anddrying the coatings. The coverage of the dye layer is about 0.2 to 5.0g/m², preferably about 0.4 to 2.0 g/m², on a dry basis. The content ofthe sublimable dye in the dye layer is suitably 5 to 90% by weight,preferably 10 to 70% by weight, based on the dye layer.

[0095] The heat-fusion ink layer as the thermally transferable colorantlayer comprises a colorant, a binder and optional desired additives.Among organic or inorganic pigments or dyes, those having goodproperties as a recording material, for example, those, which havesatisfactory color density and are less likely to cause color change andfading upon exposure to light, heat, and temperature, are preferred asthe colorant. Colorants having black, cyan, magenta, yellow, and otherhues are usable. The binder used is composed mainly of wax and furthercomprises a mixture of a drying oil, a resin, a mineral oil, cellulose,and a rubber derivative.

[0096] Waxes include microcrystalline wax, carnauba wax, and paraffinwax. Further, other various waxes such as Fischer-Tropsh wax, varioustypes of low-molecular weight polyethylene, Japan wax, beeswax,spermaceti, insect wax, wool wax, shellac wax, candelilla wax,petrolactum, polyester wax, partially modified wax, fatty esters, andfatty amides may also be used. A vinyl chloride-vinyl acetate copolymerresin, an acrylic resin, or a combination of an acrylic resin with achlorinated rubber, a vinyl chloride-vinyl acetate copolymer resin, acellulosic resin or the like may be used as the binder used in theheat-fusion ink layer.

[0097] The heat-fusion ink layer may be formed at a coverage of about 1to 8 g/m² on a dry basis, for example, by hot melt coating, hot lacquercoating, gravure coating, gravure reverse coating, knife coating, aircoating, or roll coating a composition for a heat-fusion ink layercomprising the colorant, the binder and optional additives.

[0098] An image formation method for providing a print, which comprisesan image thermally transferred onto an object and a protective layertransferred onto the image, using the thermal transfer sheet accordingto the present invention will be described.

[0099] A thermal transfer sheet comprising a thermally transferablecolorant layer provided on a substrate sheet is first provided. Acolorant is thermally transferred from the colorant layer onto an objectto form an image. Next, a protective layer is thermally transferred froma thermal transfer sheet, comprising a thermally transferable protectivelayer provided separably on the substrate sheet, onto the image so as tocover at least the printed portion, and the substrate sheet is thenseparated.

[0100] In the thermal transfer recording method used for forming animage on an object, recording is carried out by generating thermalenergy controlled by image signals by means of a thermal head and usingthe thermal energy as energy for activating a recording material such asink. In this case, a thermal transfer sheet comprising a thermallytransferable colorant layer provided on a substrate sheet is put on topof recording paper. The laminate is passed through between a thermalhead and a platen which are under a suitable applied pressure. Thethermal head of which the temperature has been raised by energizationactivates the recording material, and an image is transferred onto therecording paper with the aid of the pressure of the platen.

[0101] Thermal transfer recording methods are classified into thermaldye sublimation transfer (sublimation-type thermal transfer) and thermalink transfer (hot melt-type thermal transfer). Any of these methods maybe used in the formation of an image in the print according to thepresent invention. A method may also be adopted wherein a combinationof, the thermal dye sublimation transfer with the thermal ink transferis used in such a manner that, for example, a gradation image portion isformed by the thermal dye sublimation transfer recording while acharacter portion is formed by the thermal ink transfer recording.

[0102] The thermal transfer recording may also be carried out by thermaltransfer means, wherein heating is carried out by laser beamirradiation, in addition to the above thermal head method.

[0103] Further, in the present invention, examples of means usable forthe thermal transfer of the protective layer include: a method wherein aprint and a thermal transfer sheet comprising a thermally transferableprotective layer provided on a substrate sheet are sandwiched betweenthe thermal head and the platen and heating is carried out from thethermal head; a heat roll method which is adopted in many ofcommercially available laminators and performs hot pressing by means ofa pair of heat rolls; a method wherein the print and the thermaltransfer sheet are sandwiched between heated flat plates or between aheated flat plate and a roll and, in this state, hot pressing is carriedout; and a thermal transfer method using laser irradiation for heating.

[0104] When a thermal head is used as the thermal transfer means for theprotective layer, the same thermal head as used in the formation of theimage may be used, or alternatively a thermal head different from thatused in the formation of the image may be used. Preferably, however,from the viewpoint of efficiency, a method is used wherein a thermaltransfer sheet, comprising a substrate sheet and, provided on thesubstrate sheet, a thermally transferable colorant layer of at least onecolor and a thermally transferable protective layer which have beenrepeatedly provided in a face serial manner, is provided and thermaltransfer is carried out onto an object by the thermal transfer meansfor, the formation of an image and the thermal transfer means for theformation of a protective layer in a single thermal transfer printer inan in-line manner.

[0105] In the transfer of a protective layer onto an object using thethermal transfer sheet according to the present invention, a protectivelayer is formed by transfer onto a thermally transferred image in apredetermined object. In this case, registration should be accuratelycarried out so that particularly a scratch-resistant layer is located onthe thermally transferred image. To this end, preferably, a method isadopted wherein a conventional detection mark for detecting the positionin the transfer of a protective layers is provided in the thermaltransfer sheet according to the present invention and is detected with adetector and this detection is interlocked with a thermal transferdevice to register the object with the transfer position of theprotective layer.

[0106] Next, the intermediate transfer recording medium according to thepresent invention will be described.

[0107]FIG. 3A is a cross-sectional view showing one embodiment of theintermediate transfer recording medium according to the presentinvention. An intermediate transfer recording medium 301 comprises asubstrate film 302 and a transfer portion 306 provided separably on thesubstrate film 302. The transfer portion 306 comprises a peel layer 303,an ionizing radiation-cured resin layer 304, and a receptive layer 305provided in that order as viewed from the substrate film 302 side.

[0108]FIG. 3B is a cross-sectional view showing one embodiment of theprint according to the present invention. A print 307 comprises anobject 309 and, provided on the object 309 in the following order, areceptive layer 305 with a thermally transferred image 308 formedthereon, an ionizing radiation-cured resin layer 304, and a releaselayer 303. In this print, a thermally transferred image is previouslyformed using a thermal transfer sheet on the receptive layer in theintermediate transfer recording medium as shown in FIG. 3A, and,thereafter, the receptive layer with a thermally transferred imageformed thereon, the ionizing radiation-cured resin layer, and therelease layer are transferred from the intermediate transfer recordingmedium onto the object so that the receptive layer with the image formedthereon comes into contact with the object, whereby the receptive layer,the ionizing radiation-cured resin layer, and the release layer arestacked on the object so as to cover the thermally transferred image.

[0109] Elements constituting the intermediate transfer recording mediumwill be described.

[0110] Substrate Film:

[0111] The substrate film 302 is not particularly limited, and the samesubstrate film as used in the conventional intermediate transferrecording medium as such may be used. Specific examples of preferredsubstrate films 302 include: thin paper, such as glassine paper,capacitor paper, or paraffin-waxed paper; and stretched or unstretchedfilms of plastics, for example, highly heat resistant polyesters, suchas polyethylene terephthalate, polyethylene naphthalate, polybutyleneterephthalate, polyphenylene sulfide, polyether ketone, or polyethersulfone, and other plastics, such as polypropylene, polycarbonate,cellulose acetate, polyethylene F derivative, polyvinyl chloride,polyvinylidene chloride, polystyrene, polyamide, polyimide,polymethylpentene, or ionomer. Composite films comprising a laminate oftwo or more materials selected from the above materials may also beused. The thickness of the substrate film 302 may be properly selectedaccording to the material so as to provide proper strength, heatresistance and other properties. In general, however, the thickness ofthe substrate film is preferably about 1 to 100 μm.

[0112] If necessary, a backside layer may be provided by a conventionalmethod on the surface of the substrate film remote from the transferportion. The backside layer is provided for preventing fusing betweenthe substrate film and a heating device, such as a thermal head, at thetime of the transfer of the transfer portion onto the object using theintermediate transfer recording medium to improve the slidability of theintermediate transfer recording medium and may comprise the same resinas used in the prior art.

[0113] Peel Layer:

[0114] The peel layer 303 generally comprises, for example, a mixture ofa resin having an acryl structure, a vinyl chloride-vinyl acetatecopolymer, and a cellulose acetate with a thermosetting acrylic resin, amelamine resin, a nitrocellulose resin, and a polyethylene wax. The useof the resin having an acryl structure as a main component isparticularly preferred. Further, a polyester resin or the like ispreferably used for regulating the adhesion between the peel layer andthe substrate film.

[0115] The peel layer may be formed by dissolving or dispersing, forexample, a resin having an acryl structure and a polyester resin in asuitable solvent to prepare a coating liquid for a peel layer, coatingthe coating liquid onto a substrate film by gravure printing, screenprinting, reverse coating using a gravure plate or the like, and dryingthe coating. The thickness of the peel layer is generally 0.1 to 10 μmon a dry basis.

[0116] Instead of the peel layer, a release layer may be provided on thesubstrate film. The release layer generally comprises a binder resin anda releasable material. Binder resins usable herein include:thermoplastic resins, for example, acrylic resins such as polymethylmethacrylate, polyethyl methacrylate, and polybutyl acrylate, vinylresins such as polyvinyl acetate, vinyl chloride-vinyl acetatecopolymer, polyvinyl alcohol, and polyvinyl butyral, and cellulosederivatives such as ethylcellulose, nitrocellulose, and celluloseacetate; and thermosetting resins such as unsaturated polyester resins,polyester resins, polyurethane resins, and aminoalkyd resins. Releasablematerials include waxes, silicone waxes, silicone resins, melamineresins, fluororesins, finely divided talc or silica, and lubricants suchas surfactants and metallic soaps.

[0117] The release layer may be formed by dissolving or dispersing theabove resin in a suitable solvent to prepare a coating liquid for arelease layer, coating the coating liquid onto a substrate film bygravure printing, screen printing, reverse coating using a gravure plateor other method, and drying the coating. The thickness of the releaselayer is generally 0.1 to 10 μm on a dry basis.

[0118] Ionizing Radiation-Cured Resin Layer:

[0119] The intermediate transfer recording medium according to thepresent invention comprises a substrate film and a transfer portionprovided on the substrate film. The transfer portion comprises at leasta peel layer, an ionizing radiation-cured resin layer, and a receptivelayer provided in that order on the substrate film.

[0120] The ionizing radiation-cured resin layer 304 mainly functions toimpart various fastness and resistance properties to the thermallytransferred image in the transfer portion 306. The ionizingradiation-cured resin layer is formed from an ionizing radiation-curableresin. The ionizing radiation-curable resin may be the same as used inthe thermal transfer sheet and may be cured in the same manner asdescribed above to form the ionizing radiation-cured resin layer.

[0121] The ionizing radiation-curable resin layer may be formed bydissolving or dispersing a composition containing the ionizingradiation-curable resin for an ionizing radiation-curable resin layer ina suitable solvent to prepare an ink for the formation of an ionizingradiation-curable resin layer, coating the ink onto the substrate film,for example, by gravure printing, screen printing, reverse coating usinga gravure plate or other means, and drying the coating.

[0122] The ionizing radiation-curable resin layer may be formed in anydesired thickness on the substrate film. However, thickness of theionizing radiation-curable resin layer is 0.1 to 50 g/m², preferablyabout 1 to 20 g/m², on a dry basis.

[0123] Receptive Layer:

[0124] The receptive layer 305 is provided, as a part of the transferportion constituting the intermediate transfer recording medium, so asto be located at the outermost surface remote from the substrate film.An image is formed by thermal transfer on the receptive layer from athermal transfer sheet having a colorant layer. The intermediatetransfer recording medium in its transfer portion with the image formedthereon is transferred onto an object, and, thus, a print is formed.

[0125] For this reason, a conventional resin material, which isreceptive to a thermally transferable colorant such as a sublimable dyeor a hot-melt ink, may be used as the material for the receptive layer.Examples of materials usable herein include: polyolefin resins such aspolypropylene; halogenated resins such as polyvinyl chloride orpolyvinylidene chloride; vinyl resins such as polyvinyl acetate, vinylchloride-vinyl acetate copolymer, ethylene-vinyl acetate copolymer, orpolyacrylic ester; polyester resins such as polyethylene terephthalateor polybutylene terephthalate; polystyrene resin; polyamide resin;resins of copolymers of olefins, such as ethylene or propylene, withother vinyl polymers; ionomers; cellulosic resins such as cellulosediastase; and polycarbonates. Vinyl chloride resins, acryl-styreneresins, or polyester resins are particularly preferred.

[0126] When the receptive layer is transferred through an adhesive layeronto an object, the receptive layer per se is not always required to beadhesive. On the other hand, when the receptive layer is transferredonto the object without through the adhesive layer, the formation of thereceptive layer using a resin material having adhesive properties, suchas vinyl chloride-vinyl acetate copolymer, is preferred.

[0127] The receptive layer may be formed by dissolving or dispersing asingle or plurality of materials, selected from the above materials,optionally mixed with various additives or the like, in a suitablesolvent such as water or an organic solvent to prepare a coating liquidfor a receptive layer, coating the coating liquid by means such asgravure printing, screen printing, or reverse coating using a gravureplate, and drying the coating. The thickness (coverage) of the receptivelayer is about 1 to 10 g/m² on a dry basis.

[0128] Object:

[0129] Next, the object 309 will be described. The intermediate transferrecording medium in its transfer portion with a thermally transferredimage formed thereon is transferred onto the object. This can provide aprint having thereon a thermally transferred image possessing excellentvarious fastness and resistance properties. The object, to which theintermediate transfer recording medium according to the presentinvention is applied, is not particularly limited, and examples thereofinclude natural pulp paper, coated paper, tracing paper, plastic filmswhich are not deformed upon exposure to heat at the time of transfer,glasses, metals, ceramics, wood, and cloths.

[0130] Regarding the form and applications of the object, there is nolimitation on the type, and examples thereof include: gold notes, suchas stock certificates, securities, deeds, passbooks, railway tickets,streetcar tickets, stamps, postage stamps, appreciation tickets,admission tickets, and other tickets; cards, such as bank cards, creditcards, prepaid cards, membership cards, greeting cards, postcards,business cards, driver's licenses, IC cards, and optical cards; cases,such as cartons and containers; bags; forms control; envelops; tags; OHPsheets; slide films; bookmarks; calendars; posters; pamphlets; menus;passports; POP goods; coasters; displays; name plates; keyboards;cosmetics; accessories such as wristwatches and lighters; stationeriessuch as report pads; building materials; panels; emblems; keys; cloths;clothes; footwears; equipment or devices such as radios, televisions,electronic calculators, and OA equipment; various sample or patternbooks; albums; and outputs of computer graphics and outputs of medicalimages.

[0131] In the formation of a thermally transferred image to produce theprint according to the present invention, the intermediate transferrecording medium and the thermal transfer sheet comprising a colorantlayer provided on a substrate are first provided. The intermediatetransfer recording medium and the thermal transfer sheet are sandwichedand pressed between a heating device, such as a thermal head, and aplaten roll so that the intermediate transfer recording medium in itstransfer portion comes into contact with the thermal transfer sheet inits colorant layer. In this state, heat is selectively generated fromthe heat generating portion in a heating device according to imageinformation to transfer the colorant in the colorant layer on thethermal transfer sheet onto the receptive layer in the intermediatetransfer recording medium, whereby an image is recorded.

[0132] The thermal transfer sheet may be a conventional thermal transfersheet. The colorant layer provided in the thermal transfer sheetcomprises a heat-fusion ink or an ink containing a sublimable dye. Thecolorant layer comprises a material properly selected according to acontemplated print from heat-fusion inks and sublimable dye inks. Acolorant layer comprising sublimable dyes used for producing printshaving excellent gradation may be formed by properly providingconventional sublimable dyes, such as yellow, magenta, cyan, and black,in a face serial manner according to need. In monochromatic binaryimages such as characters or numerals, a thermal transfer sheetcomprising a colorant layer comprising a heat-fusion ink possessingexcellent density and sharpness may be used alone, or alternatively thecolorant layer comprising the sublimable dyes and the heat-fusion inklayer may be provided in a face serial manner.

[0133] As described above, a thermally transferred image is formed as amirror image, which is not an image in the final print but an image seenwhen the final image is reflected from a mirror onto the intermediatetransfer recording medium in its transfer portion, and the intermediatetransfer recording medium and an object are pressed so that the imageface in the transfer portion with the thermally transferred image formedthereon comes into contact with the object, followed by transfer of thetransfer portion onto the object by means of heating means such as athermal head, a hot stamp, or a hot roll. Regarding the heating meansfor heating the transfer portion, in the case of a partial transfer, theuse of a thermal head or a hot stamp is preferred, while, in the case oftransfer onto the whole object, the adoption of the hot roll method ispreferred.

[0134] Thus, a print is produced wherein the receptive layer and theionizing radiation-cured resin layer have been stacked onto the objectso as to cover the thermally transferred image (see FIG. 3B).

[0135] In the formation of the print according to the present invention,a transfer portion including a specified thermally transferred image istransferred onto an object in its specified position. In this case, inorder to accurately perform registration of the position of the thermaltransfer of each color at the time of the thermal transfer of thethermally transferred image, a method is preferably adopted wherein aconventional detection mark for detecting the position in each transferis provided in the intermediate transfer recording medium and isdetected with a detector and this detection is interlocked with athermal transfer device to perform registration for thermal transfer.

EXAMPLES

[0136] The present invention will be described in more detail withreference to the following examples. In the following description,“parts” or “%” is by weight unless otherwise specified.

[0137] 1: First Thermal Transfer Sheet According to the PresentInvention

Example 1A

[0138] A 12 μm-thick polyethylene terephthalate film (Lumirror,manufactured by Toray Industries, Inc.) was provided as a substratesheet. A coating liquid for a peel layer having the followingcomposition was gravure coated on one side of the substrate sheet toform a peel layer at a coverage of 1.0 g/m² on a dry basis. A coatingliquid for a scratch-resistant layer having the following compositionwas gravure coated on the peel layer for each picture plane unit asshown in FIG. 1A to form a scratch-resistant layer at a coverage of 4.0g/m² on a dry basis. Further, as shown in FIG. 1A, a coating liquid foran adhesive layer having the following composition was gravure coated onthe scratch-resistant layer and the peel layer to form an adhesive layerat a coverage of 1.0 g/m² on a dry basis. Thus, a thermal transfer sheetof Example 1A was prepared.

[0139] After coating of each layer in the thermal transfer sheet, thecoating was dried by conventional hot-air drying. In the case of thescratch-resistant layer, however, after coating, the coating was driedby hot air and was then exposed to ultraviolet light emitted from anultraviolet exposure system (provided with a high-pressure mercury lamp(output 120 W/cm) using ozone).

[0140] A coating liquid for a heat-resistant slip layer having thefollowing composition was previously gravure coated at a coverage of 2.0g/m² on a dry basis onto the other side (backside) of the substratesheet to form the heat-resistant slip layer, and, further, aftercoating, the heat-resistant slip layer was heat aged to cure thecoating. Coating liquid for peel layer: Acrylic resin (methylmethacrylate)   80 parts Polyester resin   4 parts Methyl ethyl ketone 100 parts Toluene  100 parts Coating liquid for scratch-resistantlayer: Urethane acrylic resin  100 parts Polyfunctional urethaneacrylate   20 parts Methyl ethyl ketone  100 parts Toluene  100 partsCoating liquid for adhesive layer: Vinyl chloride-vinyl acetatecopolymer   20 parts (1000 ALK, manufactured by Denki Kagaku Kogyo K.K.)Methyl ethyl ketone   40 parts Toluene   40 parts Coating liquid forheat-resistant slip layer: Polyvinyl butyral resin  3.6 parts (S-lecBX-1, manufactured by Sekisui Chemical Co., Ltd.) Polyisocyanate 19.2parts (Burnock D 750-45, manufactured by Dainippon Ink and Chemicals,Inc.) Phosphate surfactant  2.9 parts (Plysurf A 208 S, manufactured byDai-Ichi Kogyo Seiyaku Co., Ltd.) Phosphate surfactant  0.3 part(Phosphanol RD 720, manufactured by Toho Chemical Industry Co., Ltd.)Talc (manufactured by Nippon Talc  0.2 part Co., Ltd.) Methyl ethylketone   33 parts Toluene   33 parts

Example 1B

[0141] A thermally transferable protective layer having a layerconstruction of peel layer/scratch-resistant layer/adhesive layer, whichis the same layer construction as adopted in Example 1A, was formed onthe same substrate sheet as used in the thermal transfer sheet preparedin Example 1A as shown in FIG. 1B. In this case, it is a matter ofcourse that, regarding the coating area of each layer in the thermallytransferable protective layer, the scratch-resistant layer was formed ina smaller area than the area of each of the peel layer and the adhesivelayer. The area of the scratch-resistant layer is smaller than the areaof an object in its transfer surface. Further, as shown in FIG. 1B,standard dye layers for a VDS card printer CP 510 were provided asthermally transferable colorant layers of yellow, magenta, and cyan.Thus, a thermal transfer sheet of Example 1B was prepared.

Comparative Example 1A

[0142] A thermal transfer sheet of Comparative Example. 1A was preparedin the same manner as in Example 1A, except that, in the preparation ofthe thermal transfer resin layer in the thermal transfer sheet, acoating liquid for a thermal transfer resin layer having the followingcomposition was used instead of the coating liquid used in Example 1A.

[0143] Coating Liquid for Thermal Transfer Resin Layer: Polyester resin20 parts (U-18, manufactured by Arakawa Chemical Industries, Ltd.)Methyl ethyl ketone 50 parts Toluene 50 parts

[0144] Next, prints for evaluation were provided under the followingconditions.

[0145] An object comprising a card substrate having the followingcomposition was provided. Further, a thermal printer for cards (a cardprinter CP 510, manufactured by VDS) and a thermal transfer sheetcomprising standard dye layers for the VDS card printer CP 510 wereprovided. The color separation of a photograph of a face was carriedout, and each dye was transferred onto the object according to imageinformation on yellow, magenta, and cyan obtained by the colorseparation to form a full-color photograph-like facial image. ForExample 1B, however, since the thermal transfer sheet has a thermallytransferable colorant layer (dye layer), the thermally transferablecolorant layer was used.

[0146] Composition of Material for Card Substrate:

[0147] Polyvinyl Chloride Compound (Degree of Polymerization: 800)(Content of Additives Such as stabilizer: about 10%)  100 parts Whitepigment (titanium oxide)   10 parts Plasticizer (DOP)  0.5 part

[0148] A thermally transferable protective layer was transferred fromthe above thermal transfer sheet onto the image in the print so as tocover the image, as shown in FIG. 1D, by means of the same thermalprinter for cards as used above (using the same thermal head as usedabove).

[0149] Results of Evaluation:

[0150] Prints, in which the protective layer was transferred, from thethermal transfer sheets prepared in Examples 1A and 1B, onto the image,had excellent various fastness or resistance properties such asexcellent lightfastness, chemical resistance, plasticizer resistance,solvent resistance, and weathering resistance even when exposed toconditions which had simulated very severe service conditions. Further,for the thermal transfer sheets prepared in Examples 1A and 1B, theprotective layer could be transferred onto the image on the object withgood transferability. That is, an even protective layer was transferred,and the edge of the transferred protective layer was linear.

[0151] For the thermal transfer sheet prepared in Example 1B wherein thethermally transferable colorant layer and the thermally transferableprotective layer were repeatedly formed in a face serial manner on anidentical substrate sheet, after the formation of an image on theobject, the protective layer could be subsequently transferred onto theimage to prepare a print without the replacement of the thermal transfersheet with another thermal transfer sheet. This saved a lot of time andcould realize the production of a print with high efficiency.

[0152] By contrast, the print, in which the protective layer had beentransferred from the thermal transfer sheet prepared in ComparativeExample 1A onto the image, was unsatisfactory in various fastness orresistance properties such as lightfastness, chemical resistance,plasticizer resistance, solvent resistance, and weathering resistancewhen exposed to conditions which had simulated severe serviceconditions.

[0153] 2: Second Thermal Transfer Sheet According to the PresentInvention

Example 2A

[0154] A 12 μm-thick polyethylene terephthalate film (Lumirror,manufactured by Toray Industries, Inc.) was provided as a substratesheet. A coating liquid for a peel layer having the followingcomposition was gravure coated on one side of the substrate sheet toform a peel layer at a coverage of 1.0 g/m² on a dry basis. A coatingliquid for a thermal transfer resin layer having the followingcomposition was gravure coated on the peel layer to form a thermaltransfer resin layer at a coverage of 4.0 g/m² on a dry basis. Further,a coating liquid for an adhesive layer having the following compositionwas gravure coated on the thermal transfer resin layer to form anadhesive layer at a coverage of 1.0 g/m² on a dry basis. Thus, a thermaltransfer sheet of Example 2A was prepared.

[0155] After coating of each layer in the thermal transfer sheet, thecoating was dried by conventional hot-air drying. In the case of thethermal transfer resin layer, however, after coating, the coating wasdried by hot air and was then exposed to ultraviolet light emitted froman ultraviolet exposure system (provided with a high-pressure mercurylamp (output 120 W/cm) using ozone).

[0156] A coating liquid for a heat-resistant slip layer having thefollowing composition was previously gravure coated at a coverage of 2.0g/m² on a dry basis onto the other side (backside) of the substratesheet to form the heat-resistant slip layer, and, further, aftercoating, the heat-resistant slip layer was heat aged to cure thecoating. Coating liquid for peel layer: Acrylic resin (methylmethacrylate)   80 parts Polyester resin   4 parts Methyl ethyl ketone 100 parts Toluene  100 parts Coating liquid for thermal transfer resinlayer: Urethane acrylic resin  100 parts Polyfunctional urethaneacrylate   20 parts Methyl ethyl ketone  100 parts Toluene  100 partsCoating liquid for adhesive layer: Vinyl chloride-vinyl acetatecopolymer   20 parts (1000 ALK, manufactured by Denki Kagaku Kogyo K.K.)Methyl ethyl ketone   40 parts Toluene   40 parts Coating liquid forheat-resistant slip layer: Polyvinyl butyral resin  3.6 parts (S-lecBX-1, manufactured by Sekisui Chemical Co., Ltd.) Polyisocyanate 19.2parts (Burnock D 750-45, manufactured by Dainippon Ink and Chemicals,Inc.) Phosphate surfactant  2.9 parts (Plysurf A 208 S, manufactured byDai-Ichi Kogyo Seiyaku Co., Ltd.) Phosphate surfactant  0.3 part(Phosphanol RD 720, manufactured by Toho Chemical Industry Co., Ltd.)Talc (manufactured by Nippon Talc  0.2 part Co., Ltd.) Methyl ethylketone   33 parts Toluene   33 parts

Example 2B

[0157] A thermally transferable protective layer having a layerconstruction of peel layer/thermal transfer resin layer/adhesive layer,which is the same layer construction as adopted in Example 2A, wasformed on the same substrate sheet as used in the thermal transfer sheetprepared in Example 2A. Further, as shown in FIG. 2B, standard dyelayers for a VDS card printer CP 510 were provided as thermallytransferable colorant layers of yellow, magenta, and cyan. Thus, athermal transfer sheet of Example 2B was prepared.

Comparative Example 1A

[0158] A thermal transfer sheet of Comparative Example 2A was preparedin the same manner as in Example 2A, except that, in the preparation ofthe thermal transfer resin layer in the thermal transfer sheet, acoating liquid for a thermal transfer resin layer having the followingcomposition was used instead of the coating liquid used in Example 2A.

[0159] Coating Liquid for Thermal Transfer Resin Layer: Polyester resin20 parts (U-18, manufactured by Arakawa Chemical Industries, Ltd.).Methyl ethyl ketone 50 parts Toluene 50 parts

[0160] Next, prints for evaluation were provided under the followingconditions.

[0161] An object comprising a card substrate having the followingcomposition was provided. Further, a thermal printer for cards (a cardprinter CP 510, manufactured by VDS) and a thermal transfer sheetcomprising standard dye layers for the VDS card printer CP 510 wereprovided. The color separation of a photograph of a face was carriedout, and each dye was transferred onto the object according to imageinformation on yellow, magenta, and cyan obtained by the colorseparation to form a full-color photograph-like face image. For Example2B, however, since the thermal transfer sheet has a thermallytransferable colorant layer (dye layer), the thermally transferablecolorant layer was used.

[0162] Composition of Material for Card Substrate: Polyvinyl chloridecompound (degree of  100 parts polymerization: 800) (content ofadditives such as stabilizer: about 10%) White pigment (titanium oxide)  10 parts Plasticizer (DOP)  0.5 part

[0163] A thermally transferable protective layer was transferred fromthe above thermal transfer sheet onto the image in the print so as tocover the image, as shown in FIG. 2D, by means of the same thermalprinter for cards as used above (using the same thermal head as usedabove).

[0164] Results of Evaluation:

[0165] Prints, in which the protective layer was transferred, from thethermal transfer sheets prepared in Examples 2A and 2B, onto the image,had excellent various fastness or resistance properties such asexcellent lightfastness, chemical resistance, plasticizer resistance,solvent resistance, and weathering resistance even when exposed toconditions which had simulated very severe service conditions. Further,for the thermal transfer sheets prepared in Examples 2A and 2B, theprotective layer could be transferred onto the image on the object withgood transferability. That is, an even protective layer was transferred,and the edge of the transferred protective layer was linear.

[0166] For the thermal transfer sheet prepared in Example 2B wherein thethermally transferable colorant layer and the thermally transferableprotective layer were repeatedly formed in a face serial manner on anidentical substrate sheet, after the formation of an image on theobject, the protective layer could be subsequently transferred onto theimage to prepare a print without the replacement of the thermal transfersheet with another thermal transfer sheet. This saved a lot of time andcould realize the production of a print with high efficiency.

[0167] By contrast, the print, in which the protective layer had beentransferred from the thermal transfer sheet prepared in ComparativeExample 2A onto the image, was unsatisfactory in various fastness orresistance properties such as lightfastness, chemical resistance,plasticizer resistance, solvent resistance, and weathering resistancewhen exposed to conditions which had simulated severe serviceconditions.

[0168] 3: Intermediate Transfer Recording Medium According to thePresent Invention

Example 3A

[0169] A 12 μm-thick transparent polyethylene terephthalate film wasfirst provided as a substrate film. A coating liquid for a peel layerhaving the following composition was coated by gravure reverse coatingon the surface of the substrate film, and the coating was dried to forma peel layer at a coverage of 1.0 g/m² on the substrate film.

[0170] Coating Liquid for Peel Layer: Acrylic resin (methylmethacrylate)  80 parts Polyester resin  4 parts Methyl ethyl ketone 100parts Toluene 100 parts

[0171] A coating liquid for an ionizing radiation-curable resin layerhaving the following composition was gravure coated onto the peel layerto form an ionizing radiation-curable resin layer at a coverage of 4.0g/m² on a dry basis. Further, a coating liquid for a receptive layerhaving the following composition was gravure coated on the cured resinlayer to form a receptive layer at a coverage of 2.0 g/m² on a drybasis. Thus, an intermediate transfer recording medium of Example 3A wasprepared.

[0172] After coating of each layer in the intermediate transferrecording medium, the coating was dried by conventional hot-air drying.In the case of the ionizing radiation-curable resin layer, however,after coating, the coating was dried by hot air and was then exposed toultraviolet light emitted from an ultraviolet exposure system (providedwith a high-pressure mercury lamp (output 120 W/cm) using ozone) to forman ionizing radiation-cured resin layer.

[0173] A coating liquid for a heat-resistant slip layer having thefollowing composition was previously gravure coated at a coverage of 2.0g/m² on a dry basis onto the other side (backside) of the substrate filmto form the heat-resistant slip layer, and, further, after coating, theheat-resistant slip layer was heat aged to cure the coating.

[0174] Coating Liquid for Ionizing Radiation-Curable Resin Layer:Urethane acrylic resin 100 parts Polyfunctional urethane acrylate  20parts Methyl ethyl ketone 100 parts Toluene 100 parts

[0175] Coating Liquid for Receptive Layer: Vinyl chloride-vinyl acetatecopolymer  40 parts Acrylic silicone 1.5 parts Methyl ethyl ketone  50parts Toluene  50 parts

[0176] Coating Liquid for Heat-Resistant Slip Layer: Polyvinyl butryalresin  3.6 parts (S-lec BX-1, manufactured by Sekisui Chemical Co.,Ltd.) Polyisocyanate 19.2 parts (Burnock D 750-45, manufactured byDainippon Ink and Chemicals, Inc.) Phosphate surfactant  2.9 parts(Plysurf A 208 s, manufactured by Dai-Ichi Kogyo Seiyaku Co., Ltd.)Phosphate surfactant  0.3 part (Phosphanol RD 720, manufactured by TohoChemical Industry Co., Ltd.) Talc (manufactured by Nippon Talc  0.2 partCo., Ltd.) Methyl ethyl ketone   33 parts Toluene   33 parts

Comparative Example 3A

[0177] An intermediate transfer recording medium of Comparative Example3A was prepared in the same manner as in Example 3A, except that acoating liquid for a thermal transfer resin layer having the followingcomposition was used instead of the coating liquid for the ionizingradiation-curable resin layer in the intermediate transfer recordingmedium.

[0178] Coating Liquid for Thermal Transfer Resin Layer: Polyester resin20 parts (U-18, manufactured by Arakawa Chemical Industries, Ltd.)Methyl ethyl ketone 50 parts Toluene 50 parts

[0179] Next, prints for evaluation were provided under the followingconditions.

[0180] A thermal printer for cards (a card printer CP 510, manufacturedby VDS) and a thermal transfer sheet comprising standard dye layers forthe VDS card printer CP 510 were provided. The color separation of aphotograph of a face was carried out, and each dye was transferred ontothe receptive layer in each of the intermediate transfer recording mediaprepared in the example and comparative example according to imageinformation on yellow, magenta, and cyan to form a full-colorphotograph-like facial image.

[0181] The receptive layer including the thermal transfer image and theionizing radiation-cured resin layer (the thermal transfer resin layerin the comparative example) were transferred onto an object comprising acard substrate having the following composition by means of the samethermal printer for cards as used above (using the same thermal head asused above).

[0182] Composition of Material for Card Substrate: Polyvinyl chloridecompound (degree of  100 parts polymerization: 800) (content ofadditives such as stabilizer: about 10%) White pigment (titanium oxide)  10 parts Plasticizer (DOP)  0.5 part

[0183] Results of Evaluation:

[0184] Prints, in which the ionizing radiation-cured resin layer formedin Example 3A was provided on the image, had excellent various fastnessor resistance properties such as excellent lightfastness, chemicalresistance, plasticizer resistance, solvent resistance, and weatheringresistance even when exposed to conditions which had simulated verysevere service conditions. Further, for the intermediate transferrecording medium prepared in Example 3A, the transfer portion could betransferred onto the object with good transferability. That is, thetransfer portion could be evenly transferred, and the edge of thetransferred transfer portion was sharp.

[0185] By contrast, the print, in which the resin layer formed inComparative Example 3A was provided on the image, was unsatisfactory invarious fastness or resistance properties such as lightfastness,chemical resistance, plasticizer resistance, solvent resistance, andweathering resistance when exposed to conditions which had simulatedsevere service conditions.

1. A thermal transfer sheet comprising a substrate sheet and a thermallytransferable protective layer provided on the substrate sheet, whereinthe thermally transferable protective layer comprises ascratch-resistant layer, the scratch-resistant layer is repeatedlyprovided one by one for each picture plane unit in the thermal transfersheet, and an area of the scratch-resistant layer for each picture planeunit, is smaller than an area of an object in its transfer surface. 2.The thermal transfer sheet according to claim 1, wherein the thermallytransferable protective layer comprises a peel layer, thescratch-resistant layer, and an adhesive layer provided in that order asviewed from the substrate sheet side.
 3. The thermal transfer sheetaccording to claim 2, wherein the scratch-resistant layer comprises acured product of an ionizing radiation-curable resin.
 4. A thermaltransfer sheet comprising a substrate sheet and a thermally transferableprotective layer provided on the substrate sheet, wherein the thermallytransferable protective layer comprises at least a peel layer, a thermaltransfer resin layer, and an adhesive layer provided in that order asviewed from the substrate sheet side, and the thermal transfer resinlayer comprises a cured product of an ionizing radiation-curable resin.5. The thermal transfer sheet according to claim 1, wherein a thermallytransferable colorant layer(s) for at least one color is provided on thesubstrate sheet, the thermally transferable protective layer is thenprovided on the substrate sheet so that the thermally transferablecolorant layer and the thermally transferable protective layerconstitute one picture plane unit, and a combination of the thermallytransferable colorant layer with the thermally transferable protectivelayer is repeatedly provided for constituting each picture plane unit.6. The thermal transfer sheet according to claim 3, wherein the ionizingradiation-curable resin comprises urethane-modified acrylic base resin.7. The thermal transfer sheet according to claim 3, wherein the ionizingradiation-curable resin further comprises 5 to 40 parts by weight, basedon 100 parts by weight of the urethane-modified acrylic base resin, ofan oligomer.
 8. to
 10. (Canceled)